A “stem cell” is a generic name for an undifferentiated type of body cell found in tissues of embryos, fetuses and adults, which has the potential of differentiating into a diverse range of specialized cell types.
Mesenchymal stem cells are multipotent stem cells that can differentiate into a variety of cell types, including adipocytes, osteoblasts, chondrocytes, myoblasts, neuroblasts, myocardioblasts, hepatocytes, islet beta cells, vascular cells, etc., and are known to have the function of modulating self-regeneration, cell migration, and immune responses. Based on these excellent properties, mesenchymal stem cells have been developed as a cell therapeutic agent.
Mesenchymal stem cells may be isolated from various tissues such as bone marrow, umbilical cord blood, adipose tissue, etc. However, when mesenchymal stem cells are used as an exogenous cell therapeutic agent, a limited pool of mesenchymal stem cells does not allow other available options, even in the case of low in vivo activity.
In addition, in order to apply the mesenchymal stem cells to clinical practice, it is essential to obtain a large amount of cells in initial stages and to culture them with passages, due to limited quantity of mesenchymal stem cells which can be obtained from tissues. However, mesenchymal stem cells form a very heterogeneous group during passages, which affects proliferation, differentiation, and senescence of the cells, rendering the mesenchymal stem cells difficult to be developed as therapeutic agents.
As such, in order to obtain a more homogeneous cell population having improved proliferation and differentiation capacity, there is a need to discover cell marker which can represent such a cell population.
For instance, Majore I. et al. disclose cell markers such as CD44, CD73, CD90, is and CD105 for identifying a subpopulation in mesenchymal stem cell-like cultures from human umbilical cord (Cell Column. Signal., 2009, Mar. 20;7:6). In addition, the International Society for Cellular therapy proposed cell markers such as CD19, CD34, CD45, CD73, CD90, CD105, CD166, HLA-ABC and HLA-DR. However, the above-mentioned conventional cell markers are also expressed in a heterogeneous cell population and similar expressions can also be found in fibroblast. Accordingly, such cell markers are unsuitable as cell markers which can represent a more homogeneous cell population having improved proliferation and differentiation capacity.
Thus, the present inventors have endeavored to develop mesenchymal stem cells which are useful as a cell therapeutic agent, and found that CD26, CD49f, CD146 or EGFR is a cell marker which can represent a cell population having improved proliferation and differentiation capacity.